I know how to compress piston rings to slip it into the bore , but the thing I dont know is how to fit the rings on the pistons , I belive it's useing a piston ring plier and I dont know how to use it in the right way specially with aluminum pistons because it's critical and can be scratched easily .

One more thing what is the right order for the rings which one should be on the top and which for down ? and where should I locate the gap ? , I belive its wrong to locate two gaps above each other

I use a piston ring expander tool to expand the ring just enough to slip over the piston. This is used for the two compression rings but the oil control ring can be installed easily by hand. The order is to start with the oil control ring and then the 2nd compression ring and finally the top ring. This process is demonstrated in the 2JZ worked example in the practical engine building course.